Oral Intake of Rice Bran Oil Enriched With γ-Oryzanol and Phytosterol Esters Improves Skin Conditions: A Placebo-Controlled, Randomized, Double-Blind, Parallel-Group Comparative Study

Abstract

Rice bran contains various active ingredients. γ-Oryzanol, polyphenol compounds in rice bran oil, have demonstrated efficacy in improving skin conditions in both topical application and in vitro tests. Phytosterols are expected to improve skin elasticity and water retention. A double-blind randomized clinical trial was conducted involving 70 healthy Japanese men and women aged 20–59 years to assess the effects of orally administered polyphenols and phytosterols in rice bran oil on skin conditions for 12 weeks. The primary endpoint was the water content of the stratum corneum. Transepidermal water loss, skin elasticity, sebum levels, degree of glycation, image analysis of facial skin, and questionnaire survey for subjective symptoms and safety profile were also assessed. Stratum corneum water content was significantly increased in the test product group at weeks 4, 8, and 12 than that at baseline. Compared with the placebo group, the mean change was significantly higher in the test group at weeks 8 and 12. In addition, UV spot scores were significantly reduced compared to baseline at week 4 in the placebo group, and at weeks 8 and 12 in the test capsule group. A reduction in redness scores started in the test group earlier than in the placebo group. Regarding skin satisfaction scores, only the test capsule group exhibited a significant increase from baseline at weeks 4, 8, and 12. In summary, the results confirmed that the daily oral intake of rice bran oil improved skin moisture levels, possibly due to the synergistic action of two components.